A wide variety of devices have been utilized over the years to connect flexible electrical conduit and cable to electrical boxes such as outlets, junction boxes, and the like. Two such connectors contemplated for use with non-metallic sheathed for flexible cable include those illustrated and described in U.S. Pat. Nos. 2,577,748 (which issued to D. Gillespie) and 2,744,769 (which issued to W. Roeder et al.). The electrical connector of the Gillespie patent is held in the junction box by a flange and a plurality of outwardly extending lugs. The body portion of this connector has a curved finger which extends inwardly and includes a plurality of teeth. The cable is passed through the connector in order to spring the finger and increase its angle of repose. The cable is gripped between the curved end of the finger and the opposed surface of the connector, and the opposed teeth of the finger and the connector serve to grip the cable therewithin.
The Roeder et al. bushing includes an annular shoulder 14 which engages plate of the electrical box to limit the projection of the connector through a hole formed in the box. A separate ring-like fastener having a plurality of resilient lugs 17 is held within a channel formed about the periphery of the connector, and these lugs are pushed inwardly into the channel as the connector is pushed into the hole. Once fitted within the hole, the lugs snap back into their normally extended positions to hold the connector in place. Removal of the Roeder et al. bushing from the electrical box can be achieved by prying the fastener ring out of the channel and removing it from the connector. A flat resilient gripping finger is mounted within the connector to provide a ratchet/pawl arrangement to hold the cable therewithin. As can be understood, these connectors are difficult to remove from the electrical box once in place, and the connector and cable can be disassembled only by the application of substantial and possibly destructive forces.
Other prior electrical connector devices include a split shell arrangement such as shown in U.S. Pat. Nos. 2,490,286 (which issued to N. Tornblom) and 2,945,085 (which issued to J. Billups). For example, the Billups device comprises two shell-like sections which are connected and then rotated to fit within a bulkhead of an electrical box such that its grooves interact with that bulkhead to secure the connector. At the opposite end of the connector, corresponding tabs and tab openings slide together and interlock to retain the rotated shell portions in their connecting positions. The interior of the connector can be formed with ridges in order to hold the enclosed wires in place once the connector is rotated into connected position. Such a multi-piece arrangement is relatively expensive and complicated in manufacture and use, and is not well suited for removal and/or reuse once in place.
Similarly, the Tornblom connector requires a plurality of parts such as a split snap-ring which mounts within a peripheral groove near the forward end of the split shell components. The resilient ring enables the half-shells to be compressed upon insertion of the connector into the opening of an electrical box until the edges of the hole snap into the locking grooves of the connector. Thereafter, the cable clamping screw is tightened forcing the sheet metal U-shaped arm against the cable to clamp it in place and to effectively lock the split shell portions of the connector in locked condition within the hole. Again, this connector requires a multiplicity of parts which complicates manufacture and use, and requires a number of these parts to be metallic in nature. These requirements add to the expense of the connector and detract from the convenience of use.
A number of attempts have been undertaken in the prior art to provide a connecting arrangement which avoids the conventional locknut securement of the connector to the box by providing the connecting or mounting end as an expandable unit utilizing a screw to provide the expanding pressure. One example of such a structure is shown in U.S. Pat. No. 3,174,776, which issued to K. Berger. Particularly, the Berger connector is designed for use with rigid wall conduit (i.e. those having a metallic protective tube), and features an overlapping body arrangement having an opposed pair of insertion limiting shoulders which define a semi-circular groove about the periphery of the connector. The split nature of the connector enables the opposing shoulders to be radially compressible during insertion into the electrical box opening, whereby the groove will spring outwardly upon reaching the opening to temporarily join the connector with the box. A set screw is thereafter tightened onto the electrical conduit, completing the connection between the connector and the conduit by tightening the interaction between the groove and the opening of the electrical box. However, the Berger connector teaches the use of sheet metal as the material for forming the connector, and relies in part upon the rigid nature of the conduit in order to achieve the secure connection between conduit, connector, and electrical box. The use of a set screw is often not feasible when connecting non-metallic sheathed cable, as the set screw could easily penetrate the protective covering and short out the connection.
U.S. Pat. Nos. 4,056,252 and 4,157,799 (which both issued to H. Simon) attempt to address the concerns of utilizing a set screw arrangement with non-metallic cables by providing an intermediate protective member between the pressure exerting screw and the cable. However, these connectors rely upon the set screw to provide both the binding force for securing the connector and the cable, and the radial outward force required to secure the connector to the electrical box.
U.S. Pat. No. 3,788,582, which issued to W. Swanquist, attempts to address the connection of a non-metallic sheathed cable without the use of a set screw. Particularly, the Swanquist connector includes a main bore for accepting the cable to be connected and a cross bore in which is journaled a rotary cam member. When rotated, the cam member works against the enclosed cable to indent the cable into a connector body recess, thereby securing the cable within the connector. This caming action also allegedly works to spread the segmented front portion of the connector so that the grooves of the connector firmly seat against the opening of the electrical box. While this arrangement may eliminate the objections to utilizing a set screw for non-metallic cable, it is a disadvantage to have the same mechanism providing the connection between the cable and the connector and between the connector and the electrical box. Particularly, both connections must be made simultaneously, thereby eliminating some of the flexibility in using these connectors in actual applications. It may be advantageous to complete the connection between the non-metallic cable and the connector prior to making the connection with the electrical box, or visa versa.
U.S. Pat. No. 4,687,276 (which issued to E. Stockmaster) contemplates separate connection of a ribbon cable to a cable connector, and the connection of the connector to an electrical panel. However, the Stockmaster design contemplates the attachment of a separate connector to a clip, which can then be inserted into a rectangular slot in an electrical panel. While details of the Stockmaster connector are not set forth in the patent, it appears that the arrangement requires a connector and a separate clip device, with the connector being somehow attached to the ribbon cable. U.S. Pat. No. 3,285,551 (which issued to A. Tschanz) also discloses a multi-piece connector which provides separate connections for connector/conduit and connector/support structure interfaces. The Tschanz assembly includes a slotted first end for insertion into an aperture, and a slotted, tapered second end which can be engaged onto a conduit by tightening a tapered nut 46 thereover. Once connected to a bulkhead or box, however, there is no provision for removal of the Tschanz connector.
Consequently, while a wide variety of electrical connectors have been attempted and available in the industry, heretofore there has not been available a relatively simple connector for connecting non-metallic sheathed cable to an electrical box which can provide improved flexibility and convenience in accomplishing a secure connection between the cable and an electrical box.